South Korean conservative activists burn portraits of North Korean Leader Kim Jong Il, left, and what protesters say are portraits of his son Kim Jong Un during a rally denouncing North Korea’s nuclear program Monday in front of the Munhwa Broadcasting Corp. in Seoul, South Korea.

Seoul, South Korea ? A North Korean-flagged ship under close watch in Asian waters is believed to be heading toward Myanmar carrying small arms cargo banned under a new U.N. resolution, a South Korean intelligence official said.

Still, analysts say a high seas interception — something North Korea has said it would consider an act of war — is unlikely.

The Kang Nam, accused of engaging in illicit trade in the past, is the first vessel monitored under the new U.N. sanctions designed to punish the North for its defiant nuclear test last month. The U.S. military began tracking the ship after it left a North Korean port last week on suspicion it was carrying illicit weapons.

The South Korean broadcaster YTN said today that the ship was traveling in waters 200 nautical miles southeast of Shanghai at a speed of about 10 knots, or 11.5 mph. YTN did not say where the information came from.

U.S. and Japanese military officials said they could not provide details about the whereabouts of the Kang Nam or a U.S. destroyer shadowing the vessel.

A South Korean intelligence official said Monday that his agency believes the North Korean ship is carrying small weapons and is sailing toward the Myanmar city of Yangon.

The official, who spoke on condition of anonymity citing the sensitive nature of the information, said he could provide no further details.

Myanmar’s military government, which faces an arms embargo from the U.S. and the European Union, reportedly has bought weapons from North Korea in the past.